This is the 3561st most frequent Russian word.
сериалов
"Сериалов" means "of series" (genitive plural of "сериал," which refers to TV series or shows).
The word 'сериалов' is the plural genitive form of 'сериал' and is used here to indicate the quantity of series watched.
Я посмотрел множество интересных сериалов за последние две недели.
I have watched many interesting series over the last two weeks.
Here, 'сериалов' is used as a plural genitive form showing that the dialogues belong to or are part of multiple series.
Для переводчиков часто бывает сложно передавать культурные особенности в диалогах сериалов.
For translators, it is often difficult to convey cultural nuances in the dialogues of series.
In this sentence, 'сериалов' is in the plural genitive, used to show that the discussion pertains to modern series in general.